Some people get nervous when they go to the doctor. Maybe you’re one of them. You may not enjoy all of the visit, but you understand the doctor wants to help you. (And that a treat might await you at the end.)

But if an elephant gets sick, they can’t understand a doctor’s words. They may get confused and scared, until it’s too dangerous to help them.

That’s why sleeping darts—also known as tranquilizer darts—help so much.

“It’s safer for both the humans and the elephant because the humans aren’t right next to a wild animal, and the animal isn’t being chased to try to catch it,” Dr. Tamara Grubb said. She is a veterinarian at Washington State University who specializes in anesthesiology, drugs that make animals calm, sleepy, or unable to feel pain.

Veterinarians and other scientists use sleeping darts to safely handle wild animals, including sick or injured creatures. Depending on what needs to be done, darts contain different kinds of calming drugs. Different drugs have different effects on the body and brain.

Tranquilizers help animals become less excited, while still awake. If the animal just needs to stay calm, the dart will contain tranquilizers.

But if the animal needs to be completely still and unable to feel pain, the dart will also have anesthetics. Anesthetics cause animals to sleep long enough for people to handle them.

Darts look similar to a needle and syringe, like your doctor uses. A chamber for liquid holds the drug. A plunger pushes that drug into the needle.

But the veterinarian can’t inject the drug from far away. So darts have a built-in device to do this, usually a container of tightly packed air.

“The dart flies through the air, meets resistance, and stops. When it meets resistance, the plunger makes that little charger go,” Grubb said. “It’s just like the doctor pushing the plunger on the syringe, except the doctor isn’t there.”

Once the drug enters the elephant’s muscle, changes begin. Their blood carries the drug to the brain.

Within the brain, chemicals send signals to the rest of the body. Some of those chemicals send messages that keep the elephant awake. Sleeping drugs work by shutting those chemicals off for a while.

The drug causes changes in the brain similar to a nap, but much deeper. The animal won’t have dreams, but they’ll be completely unaware. Within 15 minutes, they’re fully asleep.

Veterinarians might have only 30 minutes before the elephant wakes up, so they work quickly. They help the elephant into a safe, comfortable position, often with ropes. “It can be very complicated to support a big elephant. It takes a lot of work and a lot of people,” Grubb said.

Once the work is done, veterinarians give another drug to wake the elephant. They watch from a distance to be sure the elephant stays safe.

And the elephant wanders away, perhaps a bit confused, from the strangest nap they’ve ever had.